1. Field of the Invention
This invention relates to the field of growing a thermal oxide layer on a substrate surface to achieve low tunneling voltage through electric field enhancement.
2. Prior Art
Tunnel oxides are an essential element in the production of EEPROM devices where electrons tunnel through the tunnel oxides to charge a floating gate to a programmed state. Erasure of the EEPROM may also be accomplished by tunneling the electrons out of the floating gate through the tunnel oxide.
One known method of achieving a tunnel oxide is to grow a thin gate oxide on a silicon surface. Typically, such a thin gate oxide suffers from several problems including weak spots in the layer causing charge retention problems. In addition, manufacturing issues with a thin gate oxide including initial defects and oxide thickness control are prevalent.
It is desired to develop a thicker tunnel oxide which still allows for a low tunneling voltage and which can be manufactured predictably and with a minimum of difficulty.